problem with inbound sip limitation with blast groups

I am setting up inbound calling on my SIP trunk. I have run into a problem with inbound sip limitation with blast groups. If I have a certain number of users (more than 8), the initial blast group just rings and goes nowhere. I have confirmed this with Cisco support, but I am guessing that there is a workaround or trick to do what I need to. Thanks for your help.

Similar yes, but not exactly. I have blast groups with 15-18 phones. Is your phone system working on a SIP trunk? Do you know of any hard limitations with blast groups on a SIP trunk? If so, can you find a way to work around it?